does anyone know if i can fit 33 12.50's on my new pro comp 15x8 rims ?thanks

The "approved" rim width range for 33x12.5-15 is 8.5" to 11". You can physically do it but the manufacturer may not stand behind them if you have problems. (Since you used them outside their approved application.) Realistically you shouldn't have any serious problems. They will balloon a little more and might wear in the center a little faster than if you used a 9" or 10" wide rim.